Allow parsing empty RTCP TargetBitrate messages, but stop sending them.

webrtc/modules/rtp_rtcp/source/rtcp_packet/target_bitrate_unittest.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 36 matching lines @@
   ExpectBirateItemEquals(BitrateItem(0, 0, 0x010203), bitrates[0]);
   ExpectBirateItemEquals(BitrateItem(0, 1, 0x020304), bitrates[1]);
   ExpectBirateItemEquals(BitrateItem(1, 0, 0x030405), bitrates[2]);
   ExpectBirateItemEquals(BitrateItem(1, 1, 0x040506), bitrates[3]);
 }
 
 }  // namespace
 
 TEST(TargetBitrateTest, Parse) {
   TargetBitrate target_bitrate;
-  EXPECT_TRUE(target_bitrate.Parse(kPacket, kPacketLengthBlocks));
+  target_bitrate.Parse(kPacket, kPacketLengthBlocks);
   CheckBitrateItems(target_bitrate.GetTargetBitrates());
 }
 
 TEST(TargetBitrateTest, FullPacket) {
   const size_t kXRHeaderSize = 8;  // RTCP header (4) + SSRC (4).
   const size_t kTotalSize = kXRHeaderSize + sizeof(kPacket);
   uint8_t kRtcpPacket[kTotalSize] = {2 << 6, 207,  0x00, (kTotalSize / 4) - 1,
                                      0x12,   0x34, 0x56, 0x78};  // SSRC.
   memcpy(&kRtcpPacket[kXRHeaderSize], kPacket, sizeof(kPacket));
   rtcp::ExtendedReports xr;
@@ skipping 11 matching lines @@
   target_bitrate.AddTargetBitrate(1, 0, 0x030405);
   target_bitrate.AddTargetBitrate(1, 1, 0x040506);
 
   uint8_t buffer[sizeof(kPacket)] = {};
   ASSERT_EQ(sizeof(kPacket), target_bitrate.BlockLength());
   target_bitrate.Create(buffer);
 
   EXPECT_EQ(0, memcmp(kPacket, buffer, sizeof(kPacket)));
 }
 
+TEST(TargetBitrateTest, ParseNullBitratePacket) {
+  const uint8_t kNullPacket[] = {TargetBitrate::kBlockType, 0x00, 0x00, 0x00};
+  TargetBitrate target_bitrate;
+  target_bitrate.Parse(kNullPacket, 0);
+  EXPECT_TRUE(target_bitrate.GetTargetBitrates().empty());
+}
+
 }  // namespace webrtc